The present invention relates to a steering drive axle assembly, and is more particularly directed to an improved type of steering drive axle assembly which ensures a large steering angle and effective hermetical sealing for retention of lubricant and protection of an incorporated constant velocity universal joint.
The conventional steering drive axle assembly comprises a wheel driving axle means, a steering means for turning a vehicle and a constant velocity universal joint connecting a drive shaft and a driven shaft of the axle means together so as to provide a universal driving connection therebetween at a constant velocity. As is well known in the art, the universal joint should be hermetically sealed by suitable sealing arrangements in order to keep out dirt and moisture and prevent the escape of lubricant contained therein. In the conventional structure of a steering drive axle assembly with sealing arrangements, it was almost impossible to provide a sufficient steering angle due to the fact that the sealing arrangements interfere with the steering mobility. More particularly, as can be readily seen from a typical example of the known structure as illustrated in FIGS. 3a and 3b, the conventional assembly has the disadvantage that the maximum steering angle .beta. indicated in FIG. 3b is inevitably limited to approximately 30.degree.. The steering angle is limited because when a wheel mounting spindle 1 swings horizontally in one direction about the vertical axis of a pair of coaxially spaced king pins 2, an outer end portion 3 of the steering knuckle 4, where it is bolted to the spindle 1, will very shortly come into collision with the opening end 5 of a bell-shaped member 6. Further, an inner end portion 7 of the steering knuckle 4, where a sealing member 8 is mounted, will also very shortly come into collision with the root of the reduced portion 9 of the bell-shaped member 6. Said collision in a very short time can be avoided only by reducing an effective sealing area S.sub.2 (FIG. 3b) on the periphery of the bell-shaped member 6, since the structure does not permit a sufficient angular departure of said portion 7 from said root or that of said portion 3 from said opening end 5. Thus, in the conventional assembly as described in the foregoing, the pivotal movement of the wheel mounting spindle about the king pin axis was limited to a small and insufficient range. As a result, the steering mobility has not been satisfactory.
In order to solve the above mentioned problems, various attempts have been made, wherein one example permits more than 30.degree. steering angle but gives up provision of the sealing arrangements and/or employment of a constant velocity universal joint. This example encounters different disadvantages well known to those skilled in the art. Another example employs a flexible boot-type seal instead of desirable spherical seal. However, it is still difficult to obtain more than a 30.degree. steering angle due to limited elasticity of the boot per se. A further example utilizes a combination of a non-seal type arrangement with a known Double-Cardan type constant velocity universal joint. This last example permits a large steering angle, however, its specific structure always invites a larger dimension, which is of fatal disadvantage for use with small-sized vehicles.
Accordingly, one object of the present invention is to provide an improved steering drive axle assembly which eliminates the problems of the prior art as set forth hereinabove.
Another object of the present invention is to provide a novel steering drive axle assembly with sealing arrangements which permits a larger steering angle.
A further object of the present invention is to provide a steering drive axle assembly with sealing arrangements which is capable of increasing the maximum steering angle up to approximately 42.degree..
A still further object of the present invention is to provide a steering drive axle assembly with sealing arrangements which permits incorporating a constant velocity universal joint therewith without inviting undesirable large dimension.
A yet further object of the present invention is to provide a steering drive axle assembly which permits effective spherical sealing for lubricant retention and protection of an incorporated constant velocity universal joint.
The above and other objects, features and advantages of the present invention will become more apparent from the following description of one preferred embodiment thereof taken in conjunction with the accompanying drawings. It is to be expressly understood, however, that the drawings are for purpose of illustration only and are not intended as a definition of the limits of the present invention, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from the detailed description.
In order to fulfill the above-mentioned objects of the present invention, the steering drive axle assembly with sealing arrangements according to the present invention comprises a steering knuckle having its reduced portion secured to one end of an axle housing and a socket member having its reduced portion secured to the internal extremity of a wheel mounting spindle. The socket member is supported by a pair of vertically spaced king pins, each of which is mounted respectively to an upper wall and a lower wall of the steering knuckle for movement about the king pins. The steering drive axle assembly further comprises a shell housing which includes a substantially semi-spherical portion and an integral reduced extension secured to the internal of the steering knuckle, said shell housing receiving a constant velocity universal joint. A sealing member is provided in sealing contact against the smooth spherical outer periphery of the shell housing to keep the universal joint hermetically sealed for the protection and lubricant retention.